Files.lines() is just about as fast, cleaner code.

gunnarmorling · Jan 1, 2024 · 3195596 · 3195596
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commit 3195596
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Showing 2 changed files with 30 additions and 35 deletions.
diff --git a/src/main/java/dev/morling/onebrc/CalculateAverage.java b/src/main/java/dev/morling/onebrc/CalculateAverage.java
@@ -52,14 +52,14 @@ private static class MeasurementAggregator {
     }
 
     public static void main(String[] args) throws IOException {
-//         Map<String, Double> measurements1 = Files.lines(Paths.get(FILE))
-//         .map(l -> l.split(";"))
-//         .collect(groupingBy(m -> m[0], averagingDouble(m -> Double.parseDouble(m[1]))));
-//
-//         measurements1 = new TreeMap<>(measurements1.entrySet()
-//         .stream()
-//         .collect(toMap(e -> e.getKey(), e -> Math.round(e.getValue() * 10.0) / 10.0)));
-//         System.out.println(measurements1);
+        // Map<String, Double> measurements1 = Files.lines(Paths.get(FILE))
+        // .map(l -> l.split(";"))
+        // .collect(groupingBy(m -> m[0], averagingDouble(m -> Double.parseDouble(m[1]))));
+        //
+        // measurements1 = new TreeMap<>(measurements1.entrySet()
+        // .stream()
+        // .collect(toMap(e -> e.getKey(), e -> Math.round(e.getValue() * 10.0) / 10.0)));
+        // System.out.println(measurements1);
 
         Collector<Measurement, MeasurementAggregator, ResultRow> collector = Collector.of(
                 MeasurementAggregator::new,

diff --git a/src/main/java/dev/morling/onebrc/CalculateAverage_royvanrijn.java b/src/main/java/dev/morling/onebrc/CalculateAverage_royvanrijn.java
@@ -15,9 +15,9 @@
  */
 package dev.morling.onebrc;
 
-import java.io.BufferedReader;
-import java.io.FileReader;
 import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.AbstractMap;
 import java.util.Map;
 import java.util.stream.Collectors;
@@ -37,7 +37,7 @@ public static Measurement combineWith(Measurement m1, Measurement m2) {
                     m1.min < m2.min ? m1.min : m2.min,
                     m1.max > m2.max ? m1.max : m2.max,
                     m1.sum + m2.sum,
-                    m1.count()+m2.count
+                    m1.count + m2.count
             );
         }
 
@@ -52,33 +52,28 @@ private double round(double value) {
 
     public static void main(String[] args) throws IOException {
 
-        long before = System.currentTimeMillis();
+//        long before = System.currentTimeMillis();
 
-        // Function to map
-        try (BufferedReader br = new BufferedReader(new FileReader(FILE))) {
+        Map<String, Measurement> resultMap = Files.lines(Path.of(FILE)).parallel()
+                .map(record -> {
+                    // Map to <String,double>
+                    int pivot = record.indexOf(";");
+                    String key = record.substring(0, pivot);
+                    double measured = Double.parseDouble(record.substring(pivot + 1));
+                    return new AbstractMap.SimpleEntry<>(key, measured);
+                })
+                .collect(Collectors.toConcurrentMap(
+                        // Combine/reduce:
+                        AbstractMap.SimpleEntry::getKey,
+                        entry -> new Measurement(entry.getValue()),
+                        Measurement::combineWith));
 
-            // Took: 124080
-            Map<String, Measurement> resultMap = br.lines().parallel()
-                    .map(record -> {
-                        // Map to <String,double>
-                        int pivot = record.indexOf(";");
-                        String key = record.substring(0, pivot);
-                        double measured = Double.parseDouble(record.substring(pivot + 1));
-                        return new AbstractMap.SimpleEntry<>(key, measured);
-                    })
-                    .collect(Collectors.toConcurrentMap(
-                            // Combine/reduce:
-                            AbstractMap.SimpleEntry::getKey,
-                            entry -> new Measurement(entry.getValue()),
-                            Measurement::combineWith));
+        System.out.print("{");
+        System.out.print(
+                resultMap.entrySet().stream().sorted(Map.Entry.comparingByKey()).map(Object::toString).collect(Collectors.joining(", ")));
+        System.out.println("}");
 
-            System.out.print("{");
-            System.out.print(
-                    resultMap.entrySet().stream().sorted(Map.Entry.comparingByKey()).map(Object::toString).collect(Collectors.joining(", ")));
-            System.out.println("}");
-        }
-
-        System.out.println("Took: " + (System.currentTimeMillis() - before));
+//        System.out.println("Took: " + (System.currentTimeMillis() - before));
 
     }
 }